Most sound masking systems project noise into an otherwise benign
environment, which causes the occupants to raise their voices
above the noise level to communicate. This eliminates the
benefit of noise masking altogether. The Dual Channel Acoustic Noise Generator project noise around the
environment's perimeter, not directly into the environment. This
approach allows for conversation at normal volumes while defeating eavesdropping
devices that rely on acoustic leakage.

The perimeter of noise that the Dual Channel Acoustic Noise Generator creates prevents the use of microphones: